Protein exchange and self recognition in myxobacteria biofilms

描述(申请人提供)：生物膜是附着在表面的微生物群落，主要分布在感染部位，在抵抗抗生素和免疫系统的杀戮方面具有重要的医学意义。在了解生物膜细胞如何相互作用以引起表型变化方面的进展受到了探索其细胞相互作用的有限策略的阻碍。在这里，我们试图通过描述一种新的过程来填补知识空白，在这种过程中，生物膜内的细胞交换它们的外膜(OM)脂蛋白，从而导致表型变化。我们的模式生物黄色粘球菌是一种社会性革兰氏阴性细菌，可以进行多细胞发育，用于探索生物膜的细胞动力学。在初步结果中，我们现在显示OM也是交换的，我们确定了转移所需的细胞蛋白质。我们还表明，仅发生在结构化生物膜中的转移涉及亲缘识别，从而使细胞将自己与其他密切相关的黄色分枝杆菌分离物区分开来。由于转移涉及成本高昂的OM材料的批量移动，我们认为这种交换过程是一种合作行为，细胞之间进行交流和共享资源。最后，我们发现转移调节了群体的扩张，并且可能通过纳米管结构来调节。我们的结果具有广泛的意义，因为真核细胞众所周知地交换细胞成分，在细菌系统中，蛋白质交换开始被认为是参与沟通和不同细胞过程的一种普遍过程。我们的基因系统已经做好了应对这些根本问题的准备。在这里，在目标1中，我们将使用遗传方法来识别参与转移的蛋白质的细胞补充，并定义它们的相互作用以及纳米管在转移中可能发挥的作用。目的2研究转移过程中亲缘关系识别的机制，明确细胞-细胞识别的遗传决定因素。目标3将确定OM交换如何调节SWAM的扩展，以及它在发育和包膜动态平衡中可能发挥的作用。这些综合努力将促进我们对生物膜细胞如何相互作用、相互识别和交换细胞材料的机械理解，这将导致有别于浮游细胞或孤立细胞的表型变化。 公共卫生相关性：生物膜是致密的微生物垫，具有重要的医学意义，因为它们是大多数微生物感染的原因。生物被膜感染很难治疗，而且费用昂贵，因为它们对宿主免疫系统和抗菌剂具有抵抗力。这一建议旨在研究生物膜中新的细胞相互作用，这可能会促进我们对生物膜的理解，从而导致改进的干预策略。

DESCRIPTION (provided by applicant): Biofilms are surface attached microbial communities that predominates infection sites, and are of keen medical importance as they resist killing by antibiotics and the immune system. Progress in understanding how biofilm cells interact to elicit phenotypic changes has been impeded by limited strategies to probe their cellular interactions. Here, we seek to fill-in knowledge gaps by describing a novel process where cells within biofilms exchange their outer membrane (OM) lipoproteins, which result in phenotypic changes. Our model organism, Myxococcus xanthus, is a social gram-negative bacterium that can undergo multicellular development, is used to probe biofilm cellular dynamics. In preliminary results we now show that OMs are also exchanged and we identify cellular proteins required for transfer. We also show that transfer, which only occurs in structured biofilms, involves kin recognition whereby cells distinguish themselves from other closely related M. xanthus isolates. As transfer involves costly bulk movement of OM material, we believe this exchange process is a form of cooperative behavior where cells communicate and share resources. Lastly, we show transfer regulates swarm expansion and may be mediated by nanotube structures. Our results have broad implications as eukaryotic cells are widely known to exchange cellular components, and in bacterial systems, protein exchange is beginning to be appreciated as a prevalent process involved in communication and diverse cellular processes. Our genetic system is well poised to tackle these fundamental issues. Here, in Aim 1 we will use genetic approaches to identify the cellular complement of proteins involved in transfer, and define their interactions an the role nanotubes might play in transfer. Aim 2 will characterize the mechanism of kin recognition in transfer and define the genetic determinant for cell-cell recognition. Aim 3 will determine how OM exchange regulates swam expansion and a role it might play in development and envelope homeostasis. These combined efforts will advance our mechanistic understanding of how biofilm cells interact, recognize one another and exchange cellular material, which results in phenotypic changes that are distinct from planktonic or isolated cells. PUBLIC HEALTH RELEVANCE: Biofilms are dense microbial mats that are medically important as they account for most microbial infections. Biofilm infections are difficult and expensive to treat because they are resistant to the host immune system and antimicrobial agents. This proposal seeks to investigate novel cell interactions in biofilms, which may advance our understanding of biofilms and consequently lead to improved intervention strategies.